Survival rates of wild babies...

[maxttu]

I have a series of questions. Please pardon my ignorance...

1. What is the survival rate of wild babies? Rough percentage is ok.

2. These babies have to dig theirselves out, correct?

3. How do they breathe if they're buried?

4. Where does the strength come from? I've read and seen where some babies emerge from their eggs, but don't really move for sometime after. Wouldn't they suffocate??

I ask all of this to ask: why do breeders excavate laid eggs?

Is it to see how many eggs are oviposited? Is it to maximize hatch rates?

If the answer for the wild babies is, survival of the fittest and only the strong survive, would that also apply to and strengthen the captive bred lines? Let the strong babies survive to create stronger lines? Or is it money driven to maximize profits?

I'm not critiquing, I'm just really curious as to why we dig up our eggs.

Thanks for reading and I look forward to some great discussion.

 

[fluxlizard]

I don't know if anyone knows the exact answers to your questions, but I can speak in some rough generalities to help you with your line of thinking.

1 survival rate for most lizards to sexually reproducting adulthood is extremely low- a few percent (less than several, sometimes more like 3). The general rule is the more the eggs that are laid and the faster the maturity rate the higher the mortality rate. Most wild chameleon species have a fairly large clutch size (compared to other other lizards), plus they may multi-clutch over the course of several months, plus most mature very rapidly (several months of age). Plus they have a very short expected lifespan and high turnover rate with fresh breeders replacing die offs. Many species grow to adulthood and reproduce and are dead in less than a year or two. So their expected survival rate from hatching to adulthood is pretty low.

2 yes. BUT natural hatching, nesting and incubation is not the same as artificial. Wild babies are up to the task, hatch simultaneously rather than over days or weeks like in captivity, and dig out together. Nesting sites are likely easy dig sites, and nests may not be as deep as some artificial nests in captivity.

3 Eggs and baby lizards need less air than you may believe. Years ago I spoke briefly with someone who was at that time one of the world's foremost researchers on lizard incubation at the university where I grew up. She was not into the pet thing- was an academic. She was using different concentrations of CO2 and O2 in her research, and when she was describing this to me my first question was how she could possibly be controlling the concentration. The answer was she was using sealed bottles (maybe baby food jars- I can't remember for sure) throughout incubation. "What about air?" was my next question. I explained that for my chameleon eggs I was poking holes with a pin in the lid of my containers for some gas exchange. She thought this was absolutely hilarious. "How much fresh air do you think those eggs would get underground?". It's been about 20 years and I've been using sealed containers for my eggs ever since with great results. Keeps water content and humidity stable and effortless to manage. When things hatch and I'm away for the weekend- they are fine even without fresh air in those sealed containers- even for entire clutches of baby bearded dragons. There is some air around the egg mass in nature- between the eggs for example (fill a jar with marbles and you will see. And as they hatch and dig out, they have enough from that space.

4 Again, captive conditions do not equal wild conditions for the babies. And see comment 3 above for better understanding. Also- you can imagine you fill a ballon with air and bury it in a substrate that will hold it's structure. If a long needle is pressed through the substrate into the ballon to pop it, the space the ballon filled will leave a cavity in the earth. That's pretty similar to eggs hatching- there is some space and enough air in there for hatchlings.

Another thought- anyone who has ever recieved lizards in shipping will understand that most shippers use sealed cardboard boxes with a styrophome cooler liner which is also usually closed without holes for ventilation. The lizards do not suffocate- there is enough air for overnight and longer. I've even recieved a few really large lizards this way and was surprised they arrive just fine- big adult tegus and iguanas. They don't need as much air as you might think.

I ask all of this to ask: why do breeders excavate laid eggs?

Is it to see how many eggs are oviposited? Is it to maximize hatch rates?

If the answer for the wild babies is, survival of the fittest and only the strong survive, would that also apply to and strengthen the captive bred lines? Let the strong babies survive to create stronger lines? Or is it money driven to maximize profits?

I can't speak for others, but I dig mine up because I feel uncomfortable about my ability to control conditions of the nest throughout incubation. Moisture content is difficult to control for example, and in my conditions, so is temperature. I have thought about using nest boxes and moving those into an "incubator" in tact which would be fine if they were designed so that I could seal them and control moisture content, but they sure would take up a lot of space unnecessarily, and that space would eventually equal money- I would have to make more space or incubators for incubation or whatever. If you have only a few lizards, no problem. If you have hundreds, it is a big problem. It is easier to dig them up and put them in something smaller. The other reason is I like to examine the eggs and watch their development- it gives me some idea about how my husbandry is going. If the females aren't getting quite enough calcium- it will show in the appearance of the eggs for example.

For maximizing hatch rates- you are probably better doing "wild incubation". The late great lizard breeding pioneer, Bert Langerwerf, used in ground outdoor terraria and experimented with several species with leaving the eggs in the ground, measuring natural temperatures, and hatch rates, etc. He found hatch rates to be near 100 pct in these conditions, with strong babies. Something to think about when thinking about survival rates- probably most wild nests have very high percentage of successful hatching and emergence from the nest. Losses occur from predation and disease and starvation and dehydration and parasitization and that sort of thing before maturity. Some species like lacerta strigata he used this method only generation after generation. But others, he tried it and then continued to dig the eggs up and incubate them artificially. If a drought happens or a flood, or a heat wave or a cold snap you cannot control that as a breeder. Also some species do not have enough warm weather in our locale to complete incubation and hatch before fall sets in after being laid- especially in latter clutches for multi-clutching species.

If you are looking at strengthening through selection- it kind of has to be done by the breeder and careful selection on his part. You get into topics that aren't too popular with the "pet" loving crowd like the choice between culling or selecting the best for your own use and sell off the weaker to someone else who may not be aware and may eventually use for breeding or the way lizards pass hands so often, they may be eventually sold or given to yet another party who uses them for breeding. There are tough choices sometimes and most breeders who aren't into it long term aren't looking down the road 10 years and probably think more about maximizing profits short term. Which is really too bad. Similarly, many "pet owners" who also happen to breed sometimes, are probably looking at "saving" an individual lizard rather than considering the genetic pool should that lizard ever reproduce if it leaves their control.

I can think of only a couple of instances where other breeders seemed interested in improving the vigor of their species through careful selection rather than improving their profit margin through selection of genetic mutations and abnormal colorations. Bert did this- keeping his lacerta strigata to maturity before selling so individuals better able to survive his outdoor terraria in Alabama would be the ones passing their genetics on in his colony, and allowing the others to die off. I don't quite have the stomach for that level of "culling" but it probably minimizes suffering over the long haul (countless future generations that have it easier because they are better adapted to captive conditions)...

 

[maxttu]

I don't know if anyone knows the exact answers to your questions, but I can speak in some rough generalities to help you with your line of thinking.

1 survival rate for most lizards to sexually reproducting adulthood is extremely low- a few percent (less than several, sometimes more like 3). The general rule is the more the eggs that are laid and the faster the maturity rate the higher the mortality rate. Most wild chameleon species have a fairly large clutch size (compared to other other lizards), plus they may multi-clutch over the course of several months, plus most mature very rapidly (several months of age). Plus they have a very short expected lifespan and high turnover rate with fresh breeders replacing die offs. Many species grow to adulthood and reproduce and are dead in less than a year or two. So their expected survival rate from hatching to adulthood is pretty low.

2 yes. BUT natural hatching, nesting and incubation is not the same as artificial. Wild babies are up to the task, hatch simultaneously rather than over days or weeks like in captivity, and dig out together. Nesting sites are likely easy dig sites, and nests may not be as deep as some artificial nests in captivity.

3 Eggs and baby lizards need less air than you may believe. Years ago I spoke briefly with someone who was at that time one of the world's foremost researchers on lizard incubation at the university where I grew up. She was not into the pet thing- was an academic. She was using different concentrations of CO2 and O2 in her research, and when she was describing this to me my first question was how she could possibly be controlling the concentration. The answer was she was using sealed bottles (maybe baby food jars- I can't remember for sure) throughout incubation. "What about air?" was my next question. I explained that for my chameleon eggs I was poking holes with a pin in the lid of my containers for some gas exchange. She thought this was absolutely hilarious. "How much fresh air do you think those eggs would get underground?". It's been about 20 years and I've been using sealed containers for my eggs ever since with great results. Keeps water content and humidity stable and effortless to manage. When things hatch and I'm away for the weekend- they are fine even without fresh air in those sealed containers- even for entire clutches of baby bearded dragons. There is some air around the egg mass in nature- between the eggs for example (fill a jar with marbles and you will see. And as they hatch and dig out, they have enough from that space.

4 Again, captive conditions do not equal wild conditions for the babies. And see comment 3 above for better understanding. Also- you can imagine you fill a ballon with air and bury it in a substrate that will hold it's structure. If a long needle is pressed through the substrate into the ballon to pop it, the space the ballon filled will leave a cavity in the earth. That's pretty similar to eggs hatching- there is some space and enough air in there for hatchlings.

Another thought- anyone who has ever recieved lizards in shipping will understand that most shippers use sealed cardboard boxes with a styrophome cooler liner which is also usually closed without holes for ventilation. The lizards do not suffocate- there is enough air for overnight and longer. I've even recieved a few really large lizards this way and was surprised they arrive just fine- big adult tegus and iguanas. They don't need as much air as you might think.



I can't speak for others, but I dig mine up because I feel uncomfortable about my ability to control conditions of the nest throughout incubation. Moisture content is difficult to control for example, and in my conditions, so is temperature. I have thought about using nest boxes and moving those into an "incubator" in tact which would be fine if they were designed so that I could seal them and control moisture content, but they sure would take up a lot of space unnecessarily, and that space would eventually equal money- I would have to make more space or incubators for incubation or whatever. If you have only a few lizards, no problem. If you have hundreds, it is a big problem. It is easier to dig them up and put them in something smaller. The other reason is I like to examine the eggs and watch their development- it gives me some idea about how my husbandry is going. If the females aren't getting quite enough calcium- it will show in the appearance of the eggs for example.

For maximizing hatch rates- you are probably better doing "wild incubation". The late great lizard breeding pioneer, Bert Langerwerf, used in ground outdoor terraria and experimented with several species with leaving the eggs in the ground, measuring natural temperatures, and hatch rates, etc. He found hatch rates to be near 100 pct in these conditions, with strong babies. Something to think about when thinking about survival rates- probably most wild nests have very high percentage of successful hatching and emergence from the nest. Losses occur from predation and disease and starvation and dehydration and parasitization and that sort of thing before maturity. Some species like lacerta strigata he used this method only generation after generation. But others, he tried it and then continued to dig the eggs up and incubate them artificially. If a drought happens or a flood, or a heat wave or a cold snap you cannot control that as a breeder. Also some species do not have enough warm weather in our locale to complete incubation and hatch before fall sets in after being laid- especially in latter clutches for multi-clutching species.

If you are looking at strengthening through selection- it kind of has to be done by the breeder and careful selection on his part. You get into topics that aren't too popular with the "pet" loving crowd like the choice between culling or selecting the best for your own use and sell off the weaker to someone else who may not be aware and may eventually use for breeding or the way lizards pass hands so often, they may be eventually sold or given to yet another party who uses them for breeding. There are tough choices sometimes and most breeders who aren't into it long term aren't looking down the road 10 years and probably think more about maximizing profits short term. Which is really too bad. Similarly, many "pet owners" who also happen to breed sometimes, are probably looking at "saving" an individual lizard rather than considering the genetic pool should that lizard ever reproduce if it leaves their control.

I can think of only a couple of instances where other breeders seemed interested in improving the vigor of their species through careful selection rather than improving their profit margin through selection of genetic mutations and abnormal colorations. Bert did this- keeping his lacerta strigata to maturity before selling so individuals better able to survive his outdoor terraria in Alabama would be the ones passing their genetics on in his colony, and allowing the others to die off. I don't quite have the stomach for that level of "culling" but it probably minimizes suffering over the long haul (countless future generations that have it easier because they are better adapted to captive conditions)...

Awesome response. I will have to read over it again to make sure I didn't miss anything.

I have other thoughts/comments that I'd like to share, but I'm still on the clock at work. Let me collect my and I'll get back. Thanks!

 

[kinyonga]

With veiled chameleon's in particular I dug the eggs up and incubated them in rows spread about an inch apart and had close to 100% hatch rate and 95% survival rate at the end of three months.

 

[shaunaroxanne]

I have read quite a few instances where unexpected babies start crawling out of flower pots because the female laid her eggs in there without the keeper knowing. I think one of the biggest reasons that we dig them up is because if we left them, that means mom is still in the cage with them, and she would quickly eat them.

I have done some experimenting....some eggs get laid on top of my medium, some get half-covered, and some I have burried completely. I have found zero difference in the hatchlings' size, health, or length of incubation. I have also tried vermiculite, Hatch-Rite, and pearlite. Again, no difference in my hatchlings.

 

[fluxlizard]

I have done some experimenting....some eggs get laid on top of my medium, some get half-covered, and some I have burried completely. I have found zero difference in the hatchlings' size, health, or length of incubation. I have also tried vermiculite, Hatch-Rite, and pearlite. Again, no difference in my hatchlings.

Me too.

I found that I prefer perlite because it allows more light around the eggs for examining them and I can get a better idea of how well calcified the shells are when viewing them on this substrate.

 

[maxttu]

With veiled chameleon's in particular I dug the eggs up and incubated them in rows spread about an inch apart and had close to 100% hatch rate and 95% survival rate at the end of three months.

Yes, that's how I've seen most breeders do it.

I have read quite a few instances where unexpected babies start crawling out of flower pots because the female laid her eggs in there without the keeper knowing. I think one of the biggest reasons that we dig them up is because if we left them, that means mom is still in the cage with them, and she would quickly eat them.

I have done some experimenting....some eggs get laid on top of my medium, some get half-covered, and some I have burried completely. I have found zero difference in the hatchlings' size, health, or length of incubation. I have also tried vermiculite, Hatch-Rite, and pearlite. Again, no difference in my hatchlings.

I was thinking more along the lines of pulling the laying bin out after they're oviposted, to avoid exactly what you've described.

Your results with burying the eggs are interesting. I was going to ask if anyone had buried their eggs.